Pressure differential speed sensor

ABSTRACT

A pressure differential sensing device has a housing divided into two chambers on opposite sides of a diaphragm contained therein; a first of the two chambers has conduit means adapted for connection to the inlet of a fluid pump while the other chamber has a first conduit connected to the discharge of the fluid pump and a second conduit leading to some associated device to be controlled thereby; a valve carried by the diaphragm is urged into seating engagement with the inlet end of the second conduit by a spring so as to prevent communication between the other chamber and the second conduit whenever the differential of pressure between the pump inlet and pump outlet is less than a predetermined magnitude.

United States Patent Bier [ Feb. 22, 1972 [72] Inventor: Kenneth C.Bier, Bloomfield Hills, Mich.

[73] Assignee: Holley Carburetor Company, Warren,

Mich.

221 Filed: July 28, 1970 211 Appl.No.: 58,815

2,361,206 10/194'4 Hoppe..... ..123/l03 EX 2,260,576 10/1941 Maybach..l23/l03EX Kostenick "123/ 103 E Hannibal et al Walker ..417/34 XPrimary Examiner-Allan D. l-lerrmann Attorney-Walter Potoroka, Sr.

[ ABSTRACT A pressure differential sensing device has a housing dividedinto two chambers on opposite sides of a diaphragm contained therein; afirst of the two chambers has conduit means adapted for connection tothe inlet 'of a fluid pump while the other chamber has a first conduitconnected to the discharge of the fluid pump and a second conduitleading to some associated device to be controlled thereby; a valvecarried by the diaphragm is urged into seating engagement with the inletend of the second conduit by a spring so as to prevent communicationbetween the other chamber and the second conduit whenever thedifferential of pressure between the pump inlet and pump outlet is lessthan a predetermined magnitude.

10 Claims, 5 Drawing Figures PRESSURE DIFFERENTIAL SPEED SENSORBACKGROUND OF THE INVENTION Heretofore various devices have beenproposed by the prior art which were intended to create an output inresponse to the attainment of a particular speed of an associated pump.Such prior art devices employed a characteristic of a rotary pump todetermine when that particular pump speed was attained. That is, it hasbeen known that in some pump installations, such as an automatic waterpump, both pump inlet and pump discharge pressure increase generallyexponentially with pump speed but that pump discharge pressure increasesat a greater rate than does pump inlet pressure. This, of course, meansthat the pressure rise across the pump is a repeatable function of pumpspeed. However, the prior art not only employed such a differential inpressure in determining when a particular speed was achieved, but alsoemployed the subsequently increasing pressure differential as the sourceof the power for causing actuation of the related device to becontrolled thereby. Since the rate of change of increase in the pressuredifferential across the pump is relatively small compared to the rate ofchange in pump speed, the net result, in the prior art, is that thesensitivity or responsiveness of the overall system is slow and that avery wide band exists at the governed range or point.

Accordingly, the invention as herein disclosed and described isprimarily concerned with the solution of the above as well as otherrelated problems.

SUMMARY OF THE INVENTION According to the invention, a pressuredifferential sensing device comprises a housing, pressure responsivemeans within said housing, a first pressure chamber formed in saidhousing at one side of said pressure responsive means, a second pressurechamber formed in said housing at the other side of said pressureresponsive means, first conduit means effective for completingcommunication between said first pressure chamber and a source ofrelatively low pressure, second conduit means effective for completingcommunication between said second pressure chamber and an associatedpressure signal receiving device, a valve seat formed about said inletof said third conduit means, spring means normally urging said pressureresponsive means in a direction toward said second pressure chamber, andvalve means within said second pres sure chamber and adapted to be attimes urged by said spring means and pressure responsive means towardseating engagement with said valve seat, said spring means beingefiective to maintain said valve means seated against said valve seatuntil the differential in pressure between said relatively low pressureand said relatively high pressure attains a predetermined minimummagnitude of pressure differential, said pressure responsive means andsaid valve means being effective to move toward said first pressurechamber against said spring means upon the attainment of saidpredetermined minimum magnitude and to expose an additional effectivesurface area for reaction by said relatively high variable pressurewithin said second pressure chamber, said inlet of said third conduitmeans being effective when said valve means moves towards said firstpressure chamber to complete communication between said second pressurechamber and said third conduit means.

Various general and specific objects and advantages of the specificobjects and advantages of the invention will become apparent whenreference is made to the following written description considered inconjunction with the accompanying drawings.

DESCRIPTION OF THE DRAWINGS In the drawings, wherein certain details orelements may be omitted from one or more views for purposes of clarity:

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in greater detailto the drawings, FIG. 1 illustrates an internal combustion engine 10, asmight be employed, for example, in an automotive vehicle, provided witha carburetor assembly 12 and coolant system 14 comprised of a radiator16, with coolant flow conduits l8 and 20, and a coolant or water pumpassembly 22 which, as is well known in the art, has an inlet forreceiving cooled water from the radiator 16 and an outlet fordischarging such cooled water into the coolant circuitry formed withinthe engine 10. The pump 22, as is well known in the art, is driven bythe engine 10 so that the rotational speed of the engine is reflected inthe speed of the pump.

Portions 24 and 26 are intended to respectively depict suitable inletand discharge taps formed on or carried by pump assembly 22 so thatconduit means 28 and 30 may be respectively connected thereto and to apressure differential sensing device or assembly 32.

FIG. 2 illustrates a graph of typical curves obtained by plottingpressure against pump speed for both the inlet and discharge sides ofthe pump assembly. That is, curve 34 depicts the typical pump dischargepressure versus speed, while curve 36 depicts the typical pump inletpressure versus speed. From an inspection of curves 34 and 36 it can beseen that a pressure differential AP occurs across the pump and thatsuch values of pressure differentials (as, for example AP, at speed 8,,and AP at speed 8;) are repeatable functions of engine speed (pump,speed) even if the absolute values of both the inlet and dischargepressures are afiected by other factors such as, for example,temperature. 7

FIG. 3 illustrates, in enlarged axial cross section, the device 32 ofFIG. 1 as comprising a housing assembly 38 consisting of housingsections 40 and 42 operatively joined to each other, as by a bent overflange portion 44, in a manner so as to peripherally retain therebetweena pressure responsive diaphragm 46 which defines two variable chambers48 and 50 on opposite sides thereof. A spring 52, situated withinchamber 48, is contained between a wall 54 of housing section 40 and asuitable spring pad or plate 56 suitable carried by diaphragm 46. Theopposite side of diaphragm 46 has a valving member 58 suitably securedthereto so as to be moveable therewith. As is shown, a passageway 60 isformed through the valve member 58, diaphragm 46 and plate 56 so as toat times complete at least a degree of communication between chambers 48and 50. The upper housing section 40 has a conduit portion 62 formedthereon which communicates with conduit 28 while the lower housingsection 42 is provided with a conduit portion 64 communicating withconduit means 30. Conduit 64 may be provided with a calibratingrestriction 66, as shown. A third conduit 68 is formed in the lowerhousing section 42 in a manner so as to have the inner disposed endterminate in a valve seating surface 70 against which the valve 58 is attimes urged by spring 52 so as to cause surface 72 thereof to be inengagement with seating surface 70.

OPERATION OF THE INVENTION Let it be assumed that P, equals pump inletpressure while P, equals pump discharge pressure and that pressure P;can be a variable pressure at times equaling pressure I, and at othertimes equaling a pressure somewhat less than pressure P,. Let it befurther assumed that the engine 10 is running and driving s A t n a...

pump assembly 22 and that a particular control function is desired tooccur at a speed of S as depicted generally on each of FIGS. 2 and 5.

With the engine and pump speed being relatively low (to the left of Sthe values of both P and P will be relatively low and the preload forceof spring 52 will be sufficient to cause the diaphragm 46 to be movedtoward chamber 50 until valve member 58 is seated against seatingsurface 70 of conduit 68. During this time conduit or passageway 60 willto some degree complete communication between conduit 68 and chamber 48so as to vent conduit 68 to pressure P,.

As should be apparent, in view of the above, during the time that valvemember 58 is so held against seating surface 70, the area of diaphragm46 which is exposed to the relatively high pressure in chamber 50 (atthis time the chamber 50 defines a closed or dead-ended space thereforecausing P to be equal to P is the total area of the diaphragm 46,between chambers 48 and 50, less the area included within the seatingsurface 70.

As engine and pump speed increase, the pressure differential acrossdiaphragm 46 also increases generally in accordance with the graph ofFIG. 2; when the speed finally reaches the predetermined speed of S theforce created by such a pressure differential is sufficient to start toovercome the preload force of spring 52 thereby causing the diaphragm 46and valve 58 secured thereto to start to move upwardly or away fromseating surface 70. However, as soon as valve 58 starts to move awayfrom seat 70, the area of valve 58 previously enclosed by seat 70 andnot exposed to pressure P now becomes exposed to the high pressure P,thereby immediately adding to the total force causing diaphragm 46 andvalve 58 to move upwardly away from seat 70.

This now completes communication between chamber 50 and conduit 68 so asto supply to conduit 68, and devices associated therewith a controlsignal, P, The actual value of P, will, of course, depend upon the valueof P, which, in turn, is dependent not only on the value of P but alsotheeffective flow area of restriction 66 (if one is employed) and theeffective flow area of bleed or vent passage 60. However, when valve 58is seated against surface 70, the value of P, will be equal to P FIG. 5graphically depicts a curve 74, representing the signal pressure P,, .asa partial overlay on dashline curves 34 and 36 respectively depictingthe P and P pressure curves. From FIG. 5 it can be seen that in the lowspeed range the pressure signal P, follows the curve 36, determined bythe relatively low pressure P,, until the speed reaches thepredetermined value of S atwhich point the valve 58 starts to open asdescribed above. This in effect, determines point 76 on the curve 74.The next portion of the curve 74 as depicted between points 76 and 78has a relatively steep slope because of the phenomenon of having agreater effective surface area of diaphragm 46 exposed to the highpressure P as soon as it begins to move upwardly away from seat 70.Accordingly, as illustrated in FIG. 5, a very slight increase in speed,AS, from S is sufficient to cause the pressure signal P, to go to themaximum value of P (or P;, as the case may be).

As should be appreciated, the invention provides .a means whereby aparticular control point can be set and achieved within very closelimits of the parameter being sensed. That is, prior art structures havebeen proposed for using the differential in pressures between P, and P,.However, such prior art structures have attempted to employ suchdifferentials, unmodified, as not only a control signal but also as theoutput for operating some related device. Since such prior art deviceswere dependent upon only the force created by the con tinually changingpressure differential, this required a very wide spread in speed betweenwhen the effective pressure signal was started to be created and whensuch signal reached its full operating value. Further, such prior artdevices required the provision of two conduits leading to the relateddevice to be operated by such differential of pressures. Such prior artdevices are believed to be best emplifled by US. Pat. No. 3,204,620issued to Brooks Walker onSept. 7, 1965.

In contrast to the prior art, it can be seen that the operative pressuresignal, P,, rapidly increases once point 76 is achieved, and that onlyone conduit 68 is necessary in order-to cause a related device 80 to beoperated by such a signal or control pressure P,. One such relateddevice 80 to be operated by such a signal or control pressure P, Onesuch related device 80 is illustrated in FIG. 4 wherein a fragmentarilyillustrated carburetor or induction passage member 82 is shown as beingcomprised of a body 84 having an induction passage 86 formedtherethrough with a throttle valve 88 situated therein and mounted forpivotal rotation on a transversely extending and journaled throttleshaft 90 provided with an actuating arm or lever 92. A suitable spring94 operatively connected as to lever 92 is effective for continuouslyurging lever 92 and throttle valve 88 generally counterclockwise to anominally closed throttle. position as shown. The induction device 82may in fact be the carburetor 12 of FIG. 1 so that opening movement ofthe throttle valve 88 causes an increase in the rate of motive fluid tothe engine 10.

A lever 96, pivoted as at 98 to a suitable support 99, has one arm 100pivotallyv connected to one end 102 of a linkage means 104 which ispivotally connected at its other end 106 to throttle lever 92. The otherarm 108 of lever 96 is pivotally connected to one end 110 of motiontransmitting linkage means 112 which, in turn, is pivotally connected atits other end 114 to an operator foot-operated throttle lever 116pivotally mounted to the vehicle floor 118 as at 120.

The motion transmitting linkage means ll2 is illustrated as beingcomprised of a housing 122 having an extension 124 fixedly securedthereto at one end thereof and containing a compression spring 126therein. A linkage member 128, slideably received through one end ofhousing 122, has an enlarged head end 130 which is acted upon by spring126. The force of spring 126 is greater than that developed by spring94. Therefore, when throttle lever 116 is rotated counterclockwise aboutpivot 120, motion transmitting linkage means 112 acts as a solidtransmitting member causing lever 96 to rotate clockwise about pivot 98,and in so doing, causes, through linkage 104, throttle valve 88 andlever, 92 to be rotated clockwise in the throttle opening direction. Aspreviously stated, this increases the rate of flow of motive fluid tothe engine l0 and, assuming normal road load conditions, increases bothvehicular and engine speed. Member 131 indicates a positive wide'openthrottle stop or abutment for limiting the maximum movement of lever 96.The device 80 is illustrated, in this instance, as comprising a housingassembly 132 composed of housing sections 134 and 136 which are joinedto each other, as by a tumed-over flange portion 138, in a manner so asto peripherally contain therebetween a pressure responsive wall memberor diaphragm 140 defining distinct chambers 142 and 144 at oppositesides thereof. Chamber 142 is vented to the atmosphere as by orificemeans 146 while chamber 144 is placed in communication with suitableconduit means 148, leading to conduit 68, as by a conduit carried byhousing section 134. A plungerlike member 152, slideably receivedthrough housing section 136, is operatively connected at one end to thediaphragm 140 so as to be moveable therewith. A spring 154, containedwithin chamber 142 and situated generally about plunger or moveableabutment 152, is employed to generally urge the diaphragm 140 in adirection toward chamber 144.

Assuming now that in FIGS. 2 and 5 denotes a desired governed maximumengine speed, it can be seen that pressure P, admitted to chamber 144will be at a value equal to P, for

the range of engine speeds to the left of 8;. As lever 96 and throttlevalve 88 are further rotated in the opening direction, engine speedincreases and pressure P, increases in accordance with segment 75 ofcurve 74 until such time as pressure P reaches point 76 (8,). At thattime valve 58 (FIG. 3) becomes unseated pennitting the signal oractuating pressure P, to become a value equal to P; which iscommunicated via conduit means 148 to chamber 144 wherein the pressureP, (or P causes diaphragm 140 to move generally in the direction ofchamber 142 causing moveable abutment 152 to move toward and abuttinglyengage a raised portion or lug 160 on lever arm 100. The diaphragm 140and member 152 thusly cause lever 96 and throttle 88 to be forciblerotated in the throttle closing direction so as to maintain the desiredselected speed 8,. Suchclosing rotation of the throttle valve 88continues even though the vehicle operator resists it by not releasingthe foot-operated throttle lever 116 because of the lost motionconnection in linkage means 112 comprised of housing 122, spring 126 andplungerlike head 130 on linkage 128.

in view of the above, it should be apparent that device 80, as shown inFIG. 1, could be any particular device or apparatus desired to beactuated in response to the attainment of a particular pump speed. Forexample, such devices could in fact be pressure responsive or pressureactuated electrical switches as well as suitable servomechanisms. Also,it should be apparent that the various elements disclosed herein couldbe substituted for by their functional equivalents. For example, it ispossible to substitute pressure responsive pistonlike members for thediaphragms. Further, even though not shown, it should be apparent thatthe spring means 52 of FIG. 3 as well as 154 of FIG. 4 could be providedwith suitable cooperating adjustment means for adjustably selecting thedesired preload and thereby variably determining the value of 8;.

Even though only one preferred embodiment of the invention has beendisclosed and described, it is apparent that other embodiments andmodifications of the invention are possible within the scope of theappended claims.

lclaim:

1. A pressure differential sensing device, comprising a housing,pressure responsive means within said housing, a first pressure chamberformed in said housing at one side of said pressure responsive means, asecond pressure chamber formed in said housing at the other side of saidpressure responsive means, first conduit means efiective for completingcommunication between said first pressure chamber and a source ofrelatively low pressure, second conduit means effective for completingcommunication between said second pressure chamber and a source ofrelatively high variable pressure, third conduit means having an inletin said second chamber and effective for at times completingcommunication between said second pressure chamber and an associatedpressure signal receiving device, a valve seat formed about said inletof said third conduit means, spring means normally urging said pressureresponsive means in a direction toward said second pressure chamber, andvalve means within said second pressure chamber and adapted to be attimes urged by said spring means and pressure responsive means towardseating engagement with said valve seat, said spring means beingeffective to maintain said valve means seated against said valve seatuntil the differential in pressure between said relatively low pressureand said relatively high pressure attains a predetermined minimummagnitude of pressure differential, said pressure responsive means andsaid valve means being effective to move toward said first pressurechamber against said spring means upon the attainment of saidpredetermined minimum magnitude and to expose an additional effectivesurface area for reaction against by said relatively high variablepressure within said second pressure chamber, said inlet of said thirdconduit means being effective when said valve means moves toward saidfirst pressure chamber to complete communication between said secondpressure chamber and said third conduit means.

2. A pressure differential sensing device according to claim 1,including additional bleed passage means formed through said pressureresponsive means and said valve means, said bleed passage means beingeffective to complete communication between said first pressure chamberand said third conduit means whenever said valve means is seated againstsaid valve seat.

3. A pressure differential sensing device according to claim 1, whereinsaid valve means is carried by said pressure responsive means includingadditional venting means formed through sai valve means and saidpressure responsive means,

said venting means being effective to complete communication betweensaid first pressure chamber and said third conduit means whenever saidvalve means is seated against said valve seat.

4. A pressure differential sensing device according to claim 1, whereinsaid spring means comprises a compression spring situated within saidfirst pressure chamber, and including restriction means in said secondconduit means.

5. A pressure differential sensing device according to claim 1, whereinsaid pressure responsive means comprises a diaphragm member, whereinsaid valve means is carried by said diaphragm member, and wherein saidspring means comprises a compression spring situated within said firstpressure chamber.

6. A pressure differential sensing device according to claim 1, whereinsaid pressure responsive means comprises a diaphragm member, whereinsaid valve means is carried by said diaphragm member, wherein saidspring means comprises a compression spring situated within said firstpressure chamber, and including additional bleed passage means formedthrough said diaphragm member and said valve means, said bleed passagemeans being effective to complete communication between said firstpressure chamber and said third conduit means whenever said valve meansis seated against said valve seat.

7. A pressure differential sensing device according to claim 1, whereinsaid pressure responsive means comprises a diaphragm member, whereinsaid valve means is carried by said diaphragm member, wherein saidspring means comprises a compression spring situated within said firstpressure chamber, including additional bleed passage means formedthrough said diaphragm member and said valve means, said bleed passagemeans being effective to complete communication between said firstpressure chamber and said third conduit means whenever said valve meansis seated against said valve seat, and including calibrated restrictionmeans situated in said second conduit means.

8. A pressure differential sensing device according to claim 1, whereinsaid source of relatively low pressure comprises a pump inlet of arotary pump assembly, and wherein said source of relatively highpressure comprises a pump discharge of a rotary pump assembly.

9. A pressure differential sensing device according to claim 3, whereinsaid source of relatively low pressure comprises a pump inlet of arotary pump assembly, wherein said source of relatively high pressurecomprises a pump discharge of a rotary pump assembly, wherein said thirdconduit means is operatively connected to a pressure responsive governordevice adapted to at times adjust the position of a throttle valve in aninduction passage for an internal combustion engine, said throttle valvebeing positionable in accordance with operator demands throughinterconnecting linkage means, and said governor device being effectivewhen said valve means is unseated from said valve seat to engage saidlinkage means so as to move said throttle valve in the closingdirection.

10. A pressure differential sensing device according to claim 9, whereinsaid governor device comprises a second housing, a second pressureresponsive member contained within said second housing, a first signalpressure chamber formed in said second housing at one side of saidsecond pressure responsive member, second spring means biasing saidsecond pressure responsive member toward said first signal pressurechamber, and movable abutment means moved by said second pressureresponsive member toward engagement with said linkage means whenever asignal pressure above a predetermined magnitude is directed from saidthird conduit means to said first signal pressure chamber.

IAIN Inna

1. A pressure differential sensing device, comprising a housing,pressure responsive means within said housing, a first pressure chamberformed in said housing at one side of said pressure responsive means, asecond pressure chamber formed in said housing at the other side of saidpressure responsive means, first conduit means effective for completingcommunication between said first pressure chamber and a source ofrelatively low pressure, second conduit means effective for completingcommunication between said second pressure chamber and a source ofrelatively high variable pressure, third conduit means having an inletin said second chamber and effective for at times completingcommunication between said second pressure chamber and an associatedpressure signal receiving device, a valve seat formed about said inletof said third conduit means, spring means normally urging said pressureresponsive means in a direction toward said second pressure chamber, andvalve means within said second pressure chamber and adapted to be attimes urged by said spring means and pressure responsive means towardseating engagement with said valve seat, said spring means beingeffective to maintain said valve means seated against said valve seatuntil the differential in pressure between said relatively low pressureand said relatively high pressure attains a predetermined minimummagnitude of pressure differential, said pressure responsive means andsaid valve means being effective to move toward said first pressurechamber against said spring means upon the attainment of saidpredetermined minimum magnitude and to expose an additional effectivesurface area for reaction against by said relatively high variablepressure within said second pressure chamber, said inlet of said thirdconduit means being effective when said valve means moves toward saidfirst pressure chamber to complete communication between said secondpressure chamber and said third conduit means.
 2. A pressuredifferential sensing device according to claim 1, including additionalbleed passage means formed through said pressure responsive means andsaid valve means, said bleed passage means being effective to completecommunication between said first pressure chamber and said third conduitmeans whenever said valve means is seated against said valve seat.
 3. Apressure differential sensing device according to claim 1, wherein saidvalve means is carried by said pressure responsive means, includingadditional venting means formed through said valve means and saidpressure responsive means, said venting means being effective tocomplete communication between said first pressure chamber and saidthird conduit means whenever said valve means is seated against saidvalve seat.
 4. A pressure differential sensing device according to claim1, wherein said spring means comprises a compression spring situatedwithin said first pressure chamber, and including restriction means insaid second conduit means.
 5. A pressure differential sensing deviceaccording to claim 1, wherein said pressure responsive means comprises adiaphragm member, wherein said valve means is carried by said diaphragmmember, and wherein said spring means comprises a compression springsituated within said first pressure chamber.
 6. A pressure differentialsensing device according to claim 1, wherein said pressure responsivemeans comprises a diaphragm member, wherein said valve means is carriedby said diaphragm member, wherein said spring means comprises acompression spring situated within said first pressure chamber, andincluding additional bleed passage means formed through said diaphragmmember and said valve means, said bleed passage means being effective tocomplete communication between said first pressure chamber and saidthird conduit means whenever said valve means is seated against saidvalve seat.
 7. A pressure differential sensing device according to claim1, wherein said pressure responsive means comprises a diaphragm member,wherein said valve means is carried by said diaphragm member, whereinsaid spring means comprises a compression spring situated within saidfirst pressure chamber, including additional bleed passage means formedthrough said diaphragm member and said valve means, said bleed passagemeans being effective to complete communication between said firstpressure chamber and said third conduit means whenever said valve meansis seated against said valve seat, and including calibrated restrictionmeans situated in said second conduit means.
 8. A pressure differentialsensing device according to claim 1, wherein said source of relativelylow pressure comprises a pump inlet of a rotary pump assembly, andwherein said source of relatively high pressure comprises a pumpdischarge of a rotary pump assembly.
 9. A pressure differential sensingdevice according to claim 3, wherein said source of relatively lowpressure comprises a pump inlet of a rotary pump assembly, wherein saidsource of relatively high pressure comprises a pump discharge of arotary pump assembly, wherein said third conduit means is operativelyconnected to a pressure responsive governor device adapted to at timesadjust the position of a throttle valve in an induction passage for aninternal combustion engine, said throttle valve being positionable inaccordance with operator demands through interconnecting linkage means,and said governor device being effective when said valve means isunseated from said valve seat to engage said linkage means so as to movesaid throttle valve in the closing direction.
 10. A pressuredifferential sensing device according to claim 9, wherein said governordevice comprises a second housing, a second pressure responsive membercontained within said second housing, a first signal pressure chamberformed in said second housing at one side of said second pressureresponsive member, second spring means biasing said second pressureresponsive member toward said first signal pressure chamber, and movableabutment means moved by said second pressure responsive member towardengagement with said linkage means whenever a signal pressure above apredetermined magnitude is directed from said third conduit means tosaid first signal pressure chamber.